Conventionally, a system such as a copying machine using cut sheet paper has used a paper feeding apparatus arranged such that a paper feed cassette or a paper feed tray is provided at a paper feed portion of a copying machine body so that paper housed in the cassette or tray is fed by a paper feed roller and conveyed along a paper conveying path.
Such a conventional paper feeding apparatus using a paper feed roller is arranged as shown in FIG. 7. In FIG. 7, a swingable bottom plate is provided inside a paper feeding cassette 1 in such a manner that the bottom plate is pivotally supported at its rear end and pushed up by a spring at its front end on the paper feeding side so as to urge paper P housed in the paper feeding cassette 1 against a paper feed roller 2.
In the paper feeding apparatus shown in this conventional example, paper P is fed out by means of rotation of paper feed roller 2. The paper P is then conveyed through a guide 3 and a registration gate 4, and further conveyed by conveying rollers 5 in timed relation to the positioning of a toner picture formed on a photosensitive drum 6, so that the toner picture formed on photosensitive drum 6 is transferred onto paper P due to the discharge of a transferring/removing corotron 7.
The paper P carrying the toner picture is sent to a fixing device 9 through a suction belt conveying device 8. The paper P is heated and pressed by fixing device 9 so that toner is fused to thereby complete a copy.
In such a paper feeding apparatus in a copying machine as described above, although paper conveying members such as the conveying rollers, the paper feed roller, the belt conveying device, and so on, are driven at speeds that are different from each other, generally, they are driven by the same motor through transmitting means such as driving belts, chains or the like. Sprockets, clutches or the like are provided on the respective shafts of the conveying members so that clutches are switched on and off in accordance with the timing of the transmitting means so as to convey paper.
Conventionally, in a system such as a copying machine, a facsimile, or the like, a paper conveying means is used in which rollers provided along a paper conveying path are rotated to thereby convey paper.
Such a roller paper-feeding apparatus in a copying machine is shown in FIG. 15. The paper feeding mechanism includes a paper feed cassette 101, paper feeding belt 102 and a paper feed roller 103. Paper housed in paper feed cassette 101 is fed by paper feeding belt 102 and paper feed roller 103 of the paper feed device and is conveyed by conveying rollers 104 along a paper conveying path. A toner picture is transferred onto the paper from a photosensitive drum 109 on the paper conveying path. The paper carrying the toner picture is fed by a conveyor belt 105 to a fixing device. The paper is then heated and pressed' by the fixing device so that toner is fused and fixed on the paper to produce a copy.
In the paper conveying roller device, as described above, a chain 106 is engaged with sprockets 107, and a sprocket of a motor 108 so that sprockets 107 are driven by the motor 108. Clutches (not shown) are provided between the sprockets 107, and shafts of rollers 103. The clutches can be switched on and off so that rollers 103 are driven in the paper feeding mode to thereby convey the paper.
In the conventional apparatus as described above, friction is created between the paper and the roller or belt when the paper is taken out of the paper feed cassette. Accordingly, slip may occur between the paper and the roller or belt, thereby rubbing the paper. This rubbing generates a paper powder.
Moreover, in the paper feeding apparatus as described above, in order to drive components such as the paper feed roller and the paper conveying rollers, it is necessary to use a combination of transmission components such as motors, chains, timing belts, etc., and components such as clutches, on the respective shafts of the rollers. Accordingly, a relatively large space is required to house those components, resulting in design problems. The requirement for a control device so as to provide, for example, timing for feeding the paper further adds to the complexity and cost of the feeding apparatus. This increased cost precludes any reduction in the manufacturing cost of a copying machine.
Further, in the conventional apparatus as described above, it is necessary that driving force transmitting components such as chains, timing belts, etc., be provided between the components and each of the conveying rollers. It is also necessary that the reduction ratio of sprockets is set accurately in order to adjust the conveying speed of the respective conveying rollers. It is also necessary to provide clutches for intermittently driving each of the conveying rollers, and in addition to the clutches, it is necessary to provide a control system corresponding to each clutch for controlling the clutch.
When driving-force transmitting components such as a chain is provided between a motor and each of the conveying rollers, it is necessary that a number of intermediate sprockets are provided and that the winding angles of the conveying rollers with respect to the sprockets are set in accordance with the position of the paper conveying path in a conventional paper feeding apparatus. Accordingly, the driving mechanism of a conventional paper feeding apparatus is complicated. Furthermore, problems in miniaturizing the copying machine and in making the copying machine with separate units, are associated with a conventional paper feeding apparatus. This precludes a reduction in the manufacturing cost of the paper feeding apparatus.